Rebekah, Robert, and Diana Mercer​Photo Source: Long Island Business News

Robert Mercer, secretive hedge fund billionaire and owner of Cambridge Analytica, the shadowy data company involved in Brexit and the Trump presidential campaign, is stepping down as CEO of Renaissance Technologies and selling his stake in Breitbart, extreme website that Steve Bannon described as "a platform for the alt-right."

Mercer is stepping down for "personal reasons," according to his statement, released today.

He is also cutting ties with Milo Yiannopoulos, the provocateur white supremacist and misogynist who served as technology editor of Breitbart for a time. Mercer wrote of Yiannopoulos that he had supported him in the hopes that he would promote free speech:

"But in my opinion, actions of and statements by Mr. Yiannopoulos have caused pain and divisiveness undermining the open and productive discourse that I had hoped to facilitate. I was mistaken to have supported him, and for several weeks have been in the process of severing all ties with him."

Mercer's actions may be related to the Senate Judiciary and Intelligence hearings, and the House Intelligence hearing, this week regarding social media and the 2016 election. Cambridge Analytica and Facebook worked together with the Trump campaign to target American voters based on data gathered in ways that have yet to be fully explained.

Mercer's statement can be read below. A clip from a BBC program about the 2016 presidential election, called "Secrets of Silicon Valley," can be accessed below as well.